“We need to look at the evidence and assess whether, at one end of the scale, this is systematic right through the qualifications business or is this just one or two rogue operators who have gone beyond their brief.

“Depending where it is on that scale we have the powers and we will take the action because we do not want to see the confidence in our qualifications system being undermined.”

This comes as it was announced that pupils who were expecting to face examinations this January may have their paper’s “pulled”, should their exam boards be found to have given improper guidance over expected questions.

Ofqual’s Glenys Stacey said the regulator would be “looking in detail at just these possible conflicts of interests in the provision of qualifications”.

And one of the sanctions available to Ofqual is pulling “examinations set for January and for next summer with awarding bodies providing substitute scripts”.

“We are very clear that our exam system needs fundamental reform. The revelations we have seen today show our current system is discredited… We are very clear we will take whatever action is necessary to restore faith in the exam system.”

Asked if that meant last year’s exam results have now been devalued to the point of being useless, he said:

“I don’t think that’s the right conclusion to draw but there’s clear a problem and we need to address that.”

In the wake of the Telegraph’s disclosures, Geoff Lucas, the former assistant chief executive for the Qualification and Curriculum Authority (QCA), Ofqual’s predecessor, said the examiners appeared “damned by their own words”.

He said:

“There is a line between guiding teachers about a topic and telling, giving them more than hints, clear steers, about what will be in the test.”

In recent years the Welsh exam board, the WJEC, has become increasing popular in England. Yet a series of secretive exam seminars are at the centre of concerns over the system. Undercover reporters from Telegraph went to 13 of these meetings – that could range in attendance between 20 or 100 teachers – and found that teachers were routinely given information about future questions, areas of the syllabus that would be assessed and specific words or facts students must use to answer in questions to win marks.

The seminars were usually cost between £120 to £230.

At a WJEC course held last month and recorded by the Telegraph, shows that Paul Evans, one of the chief examiners of the course, advised teachers that the compulsory question for section A of the history exam “goes through a cycle”.

“This coming summer, and there’s a slide on this later on, it’s going to be the middle bit: ‘Life in Germany 1933-39’ or for America, it will be ‘Rise and Fall of the American Economy’ … So if you know what the compulsory section is you know you’ve got to teach that.”

When a teacher pointed out that they had been told to teach the entire syllabus, Evans replied:

“There’s so little [in the course] we don’t know how we got it through. And I’m deadly serious about that. When I looked at it I thought, ‘how is this ever going to get through?'”

A spokesman for Edexcel said the examiner had been suspended – and that she regretted what she had said.

“Our examiners have a duty to uphold high academic standards at all times and like us, they should take this responsibility very seriously.

“There is strong evidence that [the examiner] has not taken her responsibility to uphold standards seriously.

“We will investigate both this issue and the allegations regarding disclosure of future exam content, and during this, suspend her from her duties as an examiner. We will not pre-judge the outcome of any investigation.”